import java.util.*;import java.io.*;import java.math.*; public class Main{ //↓見なくていいよ!ここから------------------------------------------ static class InputIterator{ ArrayList inputLine = new ArrayList(1024); int index = 0; int max; InputIterator(){ BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); while(true){ String read; try{ read = br.readLine(); }catch(IOException e){ read = null; } if(read != null){ inputLine.add(read); }else{ break; } } max = inputLine.size(); } boolean hasNext(){return (index < max);} String next(){ if(hasNext()){ String returnStr = inputLine.get(index); index++; return returnStr; }else{ throw new IndexOutOfBoundsException("これ以上入力はないよ"); } } } static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと static PrintWriter out = new PrintWriter(System.out); static void flush(){out.flush();} static void myout(Object t){out.println(t);} static void myerr(Object t){System.err.println(t);} static String next(){return ii.next();} static int nextInt(){return Integer.parseInt(next());} static long nextLong(){return Long.parseLong(next());} static ArrayList nextStrArray(){return myHanSpSplit(next());} static ArrayList myHanSpSplit(String str){return new ArrayList(Arrays.asList(str.split(" ")));} static ArrayList nextCharArray(){return mySingleSplit(next());} static ArrayList mySingleSplit(String str){return new ArrayList(Arrays.asList(str.split("")));} static ArrayList nextIntArray(){ ArrayList ret = new ArrayList(); ArrayList input = nextStrArray(); for(int i = 0; i < input.size(); i++){ ret.add(Integer.parseInt(input.get(i))); } return ret; } static ArrayList nextLongArray(){ ArrayList ret = new ArrayList(); ArrayList input = nextStrArray(); for(int i = 0; i < input.size(); i++){ ret.add(Long.parseLong(input.get(i))); } return ret; } static String kaigyoToStr(String[] list){return String.join("\n",list);} static String kaigyoToStr(ArrayList list){return String.join("\n",list);} static String hanSpToStr(String[] list){return String.join(" ",list);} static String hanSpToStr(ArrayList list){return String.join(" ",list);} public static void main(String[] args){ solve(); flush(); } //↑見なくていいよ!ここまで------------------------------------------ static void solve(){//ここがメイン関数代わり int N = nextInt(); long output = 0; final long mod = 1000000007; for(int i = 0; i < N; i++){ ArrayList tmp = nextLongArray(); long C = tmp.get(0) % mod; long D = tmp.get(1) % mod; output += ((C + 1) / 2) * D; output %= mod; } myout(output); } //Method addition frame start //Method addition frame end }